When one wishes to execute the ninja poof, one must have a fart, or air buscuit, at the ready. When said fart is about come to fruition, reach one hand inside of your pants, cup your sphincter, let it rip, and then hold it. Once in your hand you will have about 5 seconds to throw it into someone's face

to self: I gotta fart (reaches in pants and farts into hand)
to friend: hey man you gotta come check this thing out in my hand (friend walks over; throws fart in friend's face)
To Friend: haha you just got ninja poofed